Friction clutch for mechanical time fuses



March 19, 1946. Y. SEKELLA 2,397,055

FRICTION CLUTCH FOR A MECHANICAL TIME FUSE Fil ed Nov. 26, 1940 Patented Mar. 19, 1946 FRICTION CLUTCH FOR MECHANICAL TIlVIE FUSES Youston Sekella, Elmira Heights, N. Y., assignor to Bendix Aviation Corporation, South Bend, Ind, a corporation of Delaware Application November 26, 1940, Serial No. 367,175

Claims.

The present invention relates to a friction clutch for a mechanical time fuse and more particularly to a pre-set clutch for connecting the timing disc of a fuse to the chronometric driving means therefor.

In mechanical time fuses it is customary to emplo a timing disc rotated by chronometric gearing under the control of an escapement mechanism for effecting the detonation of a projectile after a predetermined time. The fuse is set by rotating the timing disc through an arc corresponding to the desired range, a slip connection being provided between the disc and the chronometric gearing to permit such rotation. It is necessary that this connection be arranged to slip when a torque is applied thereto in the setting operation without causing undue stresses in the parts which are customarily light and subject to deformation. At the same time it is necessary for this connection to connect the timing disc to the chronometric gearing in such manner that there is no possibility of slippage due to rotary accelerational forces on the projectile or the setback of the parts caused by the discharge of the projectile in use.

It is an object of the present invention to provide a novel friction clutch connection between the timing disc and the chronometric gearing of a mechanical time fuse which is accurate and reliable in operation and permanent in adjustment. It is another object to provide such a device which has a plurality of clutch surfaces of comparatively large area whereby the unit pressures thereon may be comparatively small.

It is another object to provide such a device in which the pressure of the clutch elements is maintained permanently irrespective of vibration or setback effects.

It is a further object to provide such a device in which the frictional elements are so interlocked as to prevent lost motion therebetween such as might impair the accuracy of the setting of the timing disc.

It is another object to provide such a device in which the parts are of simple construction adapted to rapid and economical methods of manufacture.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing in which:

Fig. 1 is a side elevation partly broken away and in section showing a conventional form of mechanical time fuse embodying a preferred form of the present invention;

Fi 21s a top plan view of the same;

determined rotative speed during the flight of the projectile. A sleeve 3 (Fig. 3) is fixed on the end of the chronometric shaft 2 in any suitable manner as by means of the formation of longitudinal flutes 4 on a reduced section of the shaft 2, which flutes are arranged to imbed themselves in the interior of the sleeve 3 when the sleeve is forced on the end of the shaft against a shoulder 5 forming an abutment for the sleeve.

Sleeve 3 is provided with a radial flange 6 at one end (Fig, 4), a portion 1 of non-circular cross section adjacent thereto, and a reduced cylindrical extension 8. A driving disc 9 is non-rotatably mounted on the sleeve 3 in abutting relation with the flange 6, and is immovably anchored to the sleeve both by means of the formation of a central opening H closely conforming to the noncircular portion 1 of the sleeve and alsoby means of a lug I2 engaging tightly in a notch [3 in the periphery of the flange 6. a

A driven disc I4 is rotatably mounted on the sleeve 3 in frictional engagement with the drivin disc 9, and a second driving disc 15 having an opening l6 closely conforming to the non-circular portion 1 of the sleeve 3 is non-rotatably mounted on said sleeve in frictional engagement with the driven disc I4. A timing disc I! is rotatably mounted on the sleeve 3 in frictional engagement with the second driving disc [5 and is rigidly connected to the driven disc It by means of lugs [8 extending axially from the periphery of the driven disc into tapered openings [9 in the timing disc whereby these elements are rigidly coupled together without lost motion,

Means for holding the disc in uniform frictional engagement is provided in the form of a dished spring washer 2| bearing on the upper side of the timing disc I1 and non-rotatably connected to the sleeve 3 by means of a central opening 22 conforming to the non-circular portion 1 of the sleeve. A thrust collar 23 is mounted on the reduced cylindrical extension of the sleeve 3 and is provided with a counterbore 24 (Fig. 3) permitting longitudinal adjustment of the collar over the end of the non-circular portion 1 of the sleeve. A washer 25 having an opening 25 conforming to the non-circular portion 1 of the sleeve is interposed between the thrust collar 23 and the spring washer 2!, and the parts are held in assembled relation by spinning or beading over the end of the sleeve as shown at 21 in Fig. 3. It will be understood that the operation of forming the head or flange 2 is performed by a suitable formin tool while the sleeve is being rotated, and the disc i7 held stationary in a fixture which permits observation of the torque being trans; mitted to the timing disc. By this. means the spinning operation may be continued until the proper frictional connection between the sleeve first disc, a second driving disc non-rotatably mounted on the sleeve adjacent the driven disc, a timing disc rotatably mounted on the non-circular portion of the sleeve adjacent the second driving disc, said timing disc and driven disc having interengaging means connecting them for rotation in unison, and yielding means mounted on' the sleeve pressing the discs into frictional engagement.

2. In a mechanical time fuse for explosive .7 projectiles, a chronometric drive shaft, a sleeve fixedthereon having a portion of non-circular cross section and a reduced cylindrical extension,

and the timing disc is secured. A rigid and per};

thereon to reenforce the bead 21 and prevent thepossibility of loss of adjustment or loosening f. t e pa t b eason of Secondary e bac seifects.

Inasmuch as t lug i2 is a force fit in the otch. 3.0 an *6. and the u s. "5. a e ht y wedged in the tapered openings [9 of the timing disc, it will be seen that there is no lost motion between the parts so. connected such as might impairthe' accuracy of setting of the timing disc. The areas of the frictional surfaces arequite large sov that a. moderate axial pressure of the springwasher 2i will provide a reliable frictional connection which may be therefore quite accu rately. calibrated. Moreover, since there are several frictional surfaces involved, slight variations in the condition of any one frictional surface will be averaged in such a manner as tofacilitate, uniformity in action of the frictional connection. Although but one embodiment of the invention has been shown and described in. detail, it will be lfiifildtO d at other embodiments are possible and various changes. may be. made in the design and arrangement of the parts withoutdeparting from the spirit of the invention asv de-'v fine ec aim appended hereto.

What is claimed is 1. In a mechanical time fuse for explosive. nrQLiectiles, achronometric drive shaft, a. sleeve fixed thereon having a portion. of non-circular cross section and a reduced cylindrical ex ension, a friction driving disc non rotatably mounted on thenon rcircular portion of the sleeve, a driven disc rotatably mounted on the sleeve'adjacent the a. friction. driving disc non-rotatably mounted on the non circular'portion of the sleeve, a driven disc rotatably mounted on the sleeve adjacent the first disc, a second driving disc non-rotatably mounted on the sleeve adjacent the driven disc, a timing disc rotatably mounted on the noncircular portion of the sleeve adjacent the second n lins' i a sa d m ng dis n p nin ssaid. d ven dis vi ug n s i openings, and yielding means, pressing the, discs into frictional engagement.

3. A, mechanical time fuse for explosive. projectilesasset forthin claim 2 in which,the yielding means comprises a dished. spring washer, and hrust means wqaerat ns t e ew h a ned the cylindr cal extension of the sleeve by spine nin'g over theend of the sleeve.

4, In. a mechanical, time. fuse forexplosivev p ojectiles a hronometric sha ha in duced extension, a sleeve fixed on, said extension, a pair of. driving discs. non-.rotatably mounted; on said. sleeve, a, drivendisc rotatably mounted on he sleeve. betweenthe d iv n discs, a ns. disc. rotataloly mounted. on the sleeve, and, cone. lQQtQd for. rotation with, the driven disc, and yielding, means. pressing the.discsintoirictional. n a ement, id i in dis aving tap r d openingsiand the driven. disc having peripheral ugs e tendi a. axially. into said; openin s and being wedged tightly, therein to rigidly: connect the driven disc to the timing disc,

5. A mechanical time fuse. asset. forth inclaim 4 in which the yielding, meanscomprises a dished sh ine. wa her non-rotatable. mounted on the, lee e, adjacent the timin i a p i g thrustv al er. mtat b moun e leev nd; :1 11a ge formed, on the .end of the sleeve to mainam. a onstant r ss r n. the hms members- 7 7 QUS' T N S KELLA. 

